The invention relates to a mid-frame according to the preamble of patent claim 1 as well as a gas turbine.
Such a mid-frame for a gas turbine and a gas turbine with such a mid-frame are to be taken as being known from U.S. Pat. No. 6,672,833 B2 and U.S. Pat. No. 5,180,282, for example. The mid-frame comprises at least one outer casing element, which is usually referred to as a “casing shell.” For example, the casing element is at least essentially annular in form.
The known mid-frame comprises a plurality of duct segments. The duct segments are arranged in the radial direction on the inner side of the outer casing element and are spaced in the radial direction toward the inside at least partially from the outer casing element. Furthermore, the duct segments are arranged in succession in the peripheral direction of the casing element. In other words, the duct segments are arranged one behind the other in the peripheral direction of the casing element. At least one duct through which a gas can flow is delimited at least partially at least in the radial direction by the duct segments. In relation to the direction of gas flow through the duct, the mid-frame is arranged, for example, between two turbine regions of the gas turbine. A first turbine region thereof is, for example, a high-pressure turbine region or a high-pressure turbine, while a second turbine region is, for example, a low-pressure turbine or a low-pressure turbine region of the gas turbine, in particular an aircraft engine.
The gas has a high temperature, for example, and is thus a hot gas, which, by means of the duct, is conducted in the axial direction of the gas turbine from one of the turbine regions to the other of the turbine regions.
Provided here is a segmented construction design of the duct, which is used in conjunction with the manufacturing method thereof owing to the size of the outer casing element, for example. For example, the outer casing element is manufactured by casting, that is, by means of a casting method. Moreover, stresses that can arise owing to a thermal gradient in the duct can be minimized by the segmented construction design, that is, by the use of a plurality of duct segments.
Usually, an individual mounting support is assigned to each of the duct segments, said mount also being referred to as a “hanger.” Accordingly, a segmented construction design is also used for these hangers, because the hangers are formed as structural components that are manufactured separately from one another. The respective duct segments are fastened via these hangers to the outer casing element and, in particular, hung from them. The segmented construction design of the holders is used to prevent cracks owing to high thermal stresses during operation.
Owing to the large number of hangers, however, the mounting of the hangers themselves and the duct segments, which is costly in terms of time and expense, leads overall to a mid-frame manufacture that requires considerable time and expense.